CN113445972A - Method and system for determining zonal water injection testing and regulating period of tight oil reservoir - Google Patents

Method and system for determining zonal water injection testing and regulating period of tight oil reservoir Download PDF

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CN113445972A
CN113445972A CN202110932795.XA CN202110932795A CN113445972A CN 113445972 A CN113445972 A CN 113445972A CN 202110932795 A CN202110932795 A CN 202110932795A CN 113445972 A CN113445972 A CN 113445972A
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王瑞
程嘉瑞
张明
韩继勇
孙娜娜
李震宇
车杰
惠海伟
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Xian Shiyou University
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Abstract

A method and a system for determining a zonal water injection testing and regulating period of a tight oil reservoir comprise the following steps: establishing a layered water injection multi-layer node analysis model; solving the layered water injection multi-layer node analysis model by using a stepwise search method in a nonlinear equation set numerical solution method; obtaining two-layer injection pressure and actual injection quantity under the working condition through a layered water injection multi-layer node analysis model, designing injection quantity-actual injection quantity/designed injection quantity according to the definition of single well injection distribution error, and predicting the injection distribution error; and substituting the ground pressure into a layered water injection multilayer node analysis model according to the descending trend of the ground pressure along with time to obtain the change trend of the two-layer injection pressure and the actual injection amount along with time, comparing the change trend with the injection allocation requirement, and predicting the injection allocation measuring and adjusting period. The method provides corresponding theoretical basis for determining the layered water injection characteristics and rules of the low-permeability reservoir and improving the effect of the separate injection process, can predict the separate injection error, the qualified rate of the separate injection and the injection allocation and regulation period of the layered water injection, effectively guides the practice of the layered water injection process, and improves the water injection benefit.

Description

Method and system for determining zonal water injection testing and regulating period of tight oil reservoir
Technical Field
The invention belongs to the technical field of petroleum engineering, and particularly relates to a method and a system for determining a layered water injection testing and regulating period of a tight oil reservoir.
Background
At present, the domestic stratified injection technology goes through fixed type separate injection, steel wire throwing and fishing type separate injection and cable testing and adjusting type separate injection and enters the fourth stage of intelligent separate injection, namely, under the development trend that equipment and tools are intelligentized, how to effectively use the tools aiming at water injection development is really and efficiently, the theoretical research of a pressure system of a stratified injection and production well matched with the tools is critical, and the first core problem is the determination of separate injection and injection allocation quantity. The contents related to the multi-layer multidirectional injection quantity and yield splitting technology in the latest fine water injection optimization research by utilizing big data and artificial intelligence analysis are also disclosed.
The determination method of the injection allocation amount of the zonal injection comprises a single-factor effective thickness method (H) and a formation coefficient method (KH) based on static parameters, a multi-factor split coefficient method based on production dynamics, a displacement characterization-based method and a zonal injection pressure system analysis method. Among the methods based on pressure system analysis are separate injection node analysis, complete reservoir numerical simulation, and pipe flow and seepage coupling. The node analysis method is based on the principle of conservation of mass and momentum of outflow and inflow nodes, and is simple and practical compared with other methods. The application research of node analysis in water injection process and separated layer water injection process is less at home and abroad.
The compact oil reservoir has bright water injection development characteristics, namely strong heterogeneity and large difference of water absorption between layers and in layers; and secondly, the single well and single layer water injection amount is small, and the dispensing manual or underground automatic test and allocation difficulty is high. In order to further improve the dispensing development effect, studies on dispensing injection errors and dispensing modulation cycle predictions are required.
Disclosure of Invention
The invention aims to provide a method and a system for determining a zonal water injection testing and regulating period of a tight oil reservoir, which solve the problems in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for determining a zonal water injection testing and regulating period of a tight oil reservoir comprises the following steps:
establishing a layered water injection multi-layer node analysis model on the basis of the single-layer general water injection node model;
solving the layered water injection multi-layer node analysis model until the inflow and outflow pressure difference at the bottom hole node meets the maximum value required by the inflow and outflow pressure difference of the first layer bottom hole node;
obtaining two-layer injection pressure and actual injection quantity under the working condition through a layered water injection multi-layer node analysis model, designing injection quantity-actual injection quantity/designed injection quantity according to the definition of single well injection distribution error, and predicting the injection distribution error;
and substituting the ground pressure into a layered water injection multilayer node analysis model according to the descending trend of the ground pressure along with time to obtain the change trend of the two-layer injection pressure and the actual injection amount along with time, comparing the change trend with the injection allocation requirement, and predicting the injection allocation measuring and adjusting period.
Further, in the single-layer general water injection well node analysis, the division of the pressure drop system comprises: pressure drop Deltap of ground horizontal pipe1Pressure drop Δ p of underground vertical pipe2Pressure drop Δ p of the mouth flow3And the pressure drop Δ p of the injection water in the ground4Four parts(ii) a The pipe flow pressure drop is calculated by a Darcy formula, the nozzle flow pressure drop is calculated by a nozzle flow pressure drop model, and the seepage flow pressure drop of the injected water in the ground is calculated by a plane radial flow pressure drop model; the pressure drop system division of the layered water injection well node model is characterized in that the flow pressure drop of a shaft pipe, the flow pressure drop of a nozzle and the seepage pressure drop are divided into a plurality of parts according to a plurality of layers, wherein the parts are respectively delta p2-1、…、△p2-m，△p3-1、…、△p3-m，△p4-1、△p4-mM is the number of layers of the stratified water injection;
further, the specific formula of the pressure drop of each part is as follows:
Figure BDA0003211728030000021
wherein Q is the amount of injected water, m3/d；LpIs the ground pipeline length, m; dpIs the ground pipeline inner diameter, m; a. thepIs the internal cross-sectional area of the ground pipeline, m2；
Figure BDA0003211728030000022
In the formula, Lw、HwWell depth and vertical depth, m, respectively; dwIs the inner diameter of the oil pipe, m; a. thewIs the internal cross-sectional area of the oil pipe, m2；λp、λwThe coefficients of flow friction resistance in the ground pipeline and the oil pipe are respectively, and the method is dimensionless; subscripts 1, m refer to the first and mth layers, respectively, m ═ 1, 2, …, mmax；mmaxThe maximum number of layers is injected by layers without dimension;
Figure BDA0003211728030000023
in the formula DnThe inner diameter of the water distribution nozzle is m; a. thenFor the overflow area of the water distribution nozzle, the overflow area m of a water nozzle with adjustable flavor, such as a U-shaped throttle orifice2；CdFor adjusting the flow coefficient of the tap, Cd(x)＝-3.1004x4+8.7432x3-8.8037x2+3.64x +0.2635, dimensionless; x is the opening degree of the water nozzle, 0-1.0 and is dimensionless;
Figure BDA0003211728030000031
in the formula, h is the effective thickness of the reservoir, m; kwIs water phase permeability, μm2；rwIs the wellbore radius, m; r iseThe water injection wave radius is m; s is epidermal factor, and is dimensionless; rhowAs density of the aqueous phase, kg/m 3; mu.swIs the aqueous phase viscosity, mPa.s; b iswIs the volume coefficient of the water phase and is dimensionless;
establishing a layered water injection node analysis model, taking the bottom hole flow pressure of the 1 st layer as a solution point, and using an inflow dynamic equation as shown in the formula, a layer 1 outflow dynamic equation and the 2 nd to m th layersmaxThe layer outflow dynamic equation and the relation among the injection quantities of the multiple layers form a node analysis model of the multiple-layer injection water injection well, and the node analysis model is shown as a formula (5);
Figure BDA0003211728030000032
in the formula, pjwf-inIs the bottom hole pressure of the inflow node, Pa; p is a radical ofjwf-outIs the bottom hole pressure of the outflow node, Pa; p is a radical ofrIs the formation pressure, MPa.
Furthermore, a stepwise searching method in a nonlinear equation set numerical solution method is adopted for solving, and a split coefficient (the ratio of the upper injection flow to the total injection flow) r of the injection allocation amount is firstly assumedsfjAnd the total injection quantity Q is the value rsfj epsilon (0, 1), and Q epsilon [0,1600]Then substituting into the upper layer outflow dynamic equation to calculate to obtain the total injection quantity and Q, and the upper layer injection quantity Q1And injection pressure pjwf1Then substituting the lower layer outflow dynamic equation to obtain the lower layer injection quantity Q2And injection pressure pjwf2Trial calculation and search are conducted one by one from small to large until the inflow pressure difference and the outflow pressure difference at the bottom hole node meet the requirement epsilon, and the calculation model is shown as a formula (6);
Figure BDA0003211728030000033
in the formula, QjM is the total dosage3/d；rsf-mThe split coefficient of the injection quantity is distributed for the mth layer, and the dimension is not needed; epsilon is the maximum value of the inflow pressure difference and the outflow pressure difference of the bottom hole node of the first layer, and is MPa.
Further, the dispensing error is expressed as follows:
EQ＝[Q(t2)-Q(t1)]/Q(t1) (7)
if only the formation pressure changes at two times, then there are:
[Q，Q1，…，Qm，pjwf1，…，pjwfm](t)＝fw[ (fluid Property: p)w,Bw,μw) (ground line: L)p,εp,Dp) (wellbore 1: L)w1,Hw1,εw,Dw,rw) (wellbore 2: L)w2,Hw2…, (shaft m: L)wm,Hwm(water distribution nozzle 1: 2R)n1,hn1+2Rn1,xn1) (water distribution nozzle 2: 2R)n2,hn2+2Rn2,xn2) …, (water distribution nozzle m: 2R)nm,hnm+2Rnm,xn2) (reservoir 1: h)1,re1,pr1(t),Kw1,s1,pffB (reservoir 2: h)2,re2,pr2(t),Kw2,s2) …, (reservoir m: h)m,rem,prm(t),Kwm,sm) (Water injection Process: p)j,Qmax)]；(8)
The calculation formula of the corresponding injection allocation qualified rate is as follows:
RQ＝1-EQ (9)。
further, the measured and adjusted period is defined as the time interval when the error of the two measured and adjusted injections is larger than the requirement, and the expression is as follows:
CYQ＝tn-t1when E isQ＝[Q(tn)-Q(t1)]/Q(t1)＜EQ requirementThen, n is 2,3, 4. (10)
[Q，Q1，…，Qm，pjwf1，…，pjwfm](t)＝fz[ (fluid Property: p)w,Bw,μw) (ground line: L)p,εp,Dp) (wellbore 1: L)w1,Hw1,εw,Dw,rw) (wellbore 2: L)w2,Hw2…, (shaft m: L)wm,Hwm(water distribution nozzle 1: 2R)n1,hn1+2Rn1,xn1) (water distribution nozzle 2: 2R)n2,hn2+2Rn2,xn2) …, (water distribution nozzle m: 2R)nm,hnm+2Rnm,xn2) (reservoir 1: h)1,re1,pr1(t),Kw1,s1,pffB (reservoir 2: h)2,re2,pr2(t),Kw2,s2) …, (reservoir m: h)m,rem,prm(t),Kwm,sm) (Water injection Process: p)j,Qmax)])]；(11)。
Further, the design dosage is the last measured dosage; the actual dispensing amount is the dispensing amount measured at the next time.
Further, a tight oil reservoir zonal injection testing and adjusting period determining system includes:
the model establishing module is used for establishing a layered water injection multi-layer node analysis model on the basis of the single-layer general water injection node model;
the solving module is used for solving the layered water injection multi-layer node analysis model until the inflow and outflow pressure difference at the bottom hole node meets the maximum value required by the inflow and outflow pressure difference at the bottom hole node of the first layer;
the injection allocation error prediction module is used for obtaining two-layer injection pressure and actual injection amount under the working condition through a layered water injection multi-layer node analysis model, designing injection allocation amount-actual injection allocation amount/designed injection allocation amount according to the definition of single well injection allocation error, and predicting the injection allocation error;
and the injection allocation measuring and adjusting period prediction module is used for substituting the layered water injection multi-layer node analysis model according to the descending trend of the formation pressure along with the time to obtain the change trend of the two-layer injection pressure and the actual injection amount along with the time, comparing the change trend with the injection allocation requirement and predicting the injection allocation measuring and adjusting period.
Compared with the prior art, the invention has the following technical effects:
the invention considers the pressure and flow relation of each position of a water distribution station, a water injection well mouth, a water injection well bottom water distributor and a water injection well reservoir in the layered water injection process, establishes a layered water injection well node analysis model which can be used for the analysis of a 2-layer to multi-layer layered water injection pressure system, and solves the model by adopting a step-by-step search method in a nonlinear equation set numerical solution method, compared with the traditional graphical method, the method can quickly solve when the number of layered layers is more than 2, and can theoretically solve an infinite layer, so the method has more superiority in the actual engineering calculation. And combining the node model with the separate injection measurement and regulation acquisition data to establish a prediction method of separate injection allocation error and separate injection measurement and regulation period, wherein the method can predict the separate injection allocation error, the injection allocation qualification rate and the measurement and regulation period of the separate injection, and the three parameters can be applied to effectively guide the separate injection process practice, such as: well selection basis of the layered water injection process, application limit of the layered water injection process, measurement and regulation early warning of the layered water injection process and the like. The invention provides corresponding theoretical basis for defining the characteristics and the law of the zonal injection of the low-permeability reservoir, and can obviously improve the zonal injection benefit.
Drawings
FIG. 1 is a schematic diagram of a pressure drop system in a zonal water injection well node analysis;
fig. 2 is a diagram showing a result of calculation of a dispensing cycle.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
referring to fig. 1 to 2 of the drawings,
(1) layered water injection multi-layer node analysis model and solution thereof
The node analysis model embodies the flowThe mass and momentum of the fluid entering and exiting the node are conserved, and the pressure drop calculation of each section adopts a steady-state pipe flow and a steady-state seepage mathematical model. In the water injection well node analysis of the single-layer general system, the division of a pressure drop system comprises the following steps: pressure drop Deltap of ground horizontal pipe1Pressure drop Δ p of underground vertical pipe2Pressure drop Δ p of the mouth flow3And the pressure drop Δ p of the injection water in the ground4And fourthly, the method comprises the following steps. Wherein, the pipe flow pressure drop is calculated by Darcy formula, and the nozzle flow pressure drop is calculated by nozzle flow pressure drop model (divided into fixed nozzles and adjustable nozzles)[10,17]And calculating, wherein the seepage pressure drop of the injected water under the ground is calculated by using a plane radial flow pressure drop model. The layered water injection well node model is established on the basis of a single-layer general water injection node model, and the pressure drop system division is characterized in that the flow pressure drop of a shaft pipe, the flow pressure drop of a nozzle and the seepage pressure drop are divided into a plurality of parts according to multiple layers, namely, the pressure drop is respectively delta p2-1、…、△p2-m，△p3-1、…、△p3-m，△p4-1、△p4-mAnd m is the number of layers of the separated layer water injection, as shown in figure 1.
The specific formula of each part of the pressure drop is as follows:
Figure BDA0003211728030000061
wherein Q is the amount of injected water, m3/d；LpThe length of a water injection pipeline from a water distribution station to a wellhead is m; dpIs the inner diameter of the water injection pipeline, m; a. thepIs the internal cross-sectional area of the ground pipeline, m2；
Figure BDA0003211728030000062
In the formula, Lw、HwWell depth and vertical depth, m, respectively; dwIs the inner diameter of the oil pipe, m; a. thewIs the internal cross-sectional area of the oil pipe, m2；λp、
λwThe coefficients of flow friction resistance in the ground pipeline and the oil pipe are respectively, and the method is dimensionless; the subscripts 1, m refer to the first and mth layers, respectively, m ═ 1,2，…，mmax；mmaxthe maximum number of layers for layered water injection is dimensionless.
Figure BDA0003211728030000063
In the formula DnThe inner diameter of the water distribution nozzle is m; a. thenFor distributing water nozzle overflow area, for adjustable-taste water nozzles, e.g. "U" shaped orifice, overflow area, m2；CdFor adjusting the flow coefficient of the tap, Cd(x)＝-3.1004x4+8.7432x3-8.8037x2+3.64x +0.2635, dimensionless; x is the opening degree of the water nozzle, 0-1.0 and is dimensionless;
Figure BDA0003211728030000064
in the formula, h is the effective thickness of the reservoir, m; kwIs water phase permeability, μm2；rwIs the wellbore radius, m; r iseThe water injection wave radius is m; s is epidermal factor, and is dimensionless; rhowAs density of the aqueous phase, kg/m3；μwViscosity, mPa · s, of the injected water; b iswThe volume coefficient of the injected water is dimensionless;
establishing a layered water injection node analysis model, taking the bottom hole flow pressure of the 1 st layer as a solution point, and using an inflow (pipe flow in a shaft) dynamic equation as shown in the formula, an outflow (seepage in a reservoir) dynamic equation of the 1 st layer and the 2 nd to the m thmaxAnd (3) forming a node analysis model of the multilayer separate injection water injection well by a layer outflow (seepage in a reservoir) dynamic equation and a relation between injection quantities of the plurality of layers, wherein the node analysis model is shown as a formula (5).
Figure BDA0003211728030000071
In the formula, pjwf-inIs the bottom hole pressure of the inflow node, Pa; p is a radical ofjwf-out is the bottom hole pressure of the outflow node Pa; p is a radical ofrIs the formation pressure, MPa; .
For solving the node model, the traditional method adopts a graphical method, namely, an inflow dynamic curve and an outflow dynamic curve at a certain node are drawn, and the pressure and the flow corresponding to the intersection point of two lines are the injection pressure and the water injection quantity when the system balance is met. In the double-layer water injection node analysis model, the bottom hole node is one inflow and two outflow, so that the superposition of two outflow dynamic curves needs to be considered, the injection amount of an upper layer and a lower layer can not be determined, and the graphical method can not be actually solved in the node model during layered water injection.
In contrast, the solution of the node analysis model of the patent adopts a step-by-step search method in a nonlinear equation set numerical solution method. The principle is that firstly, a split coefficient (the ratio of the upper layer injection flow to the total injection flow) r of the injection amount is assumedsfjAnd a total injection quantity Q of a value rsfj∈(0，1),Q∈[0,1600]Then substituting into the upper layer outflow dynamic equation to calculate to obtain the total injection quantity and Q, and the upper layer injection quantity Q1And injection pressure pjwf1Then substituting the lower layer outflow dynamic equation to obtain the lower layer injection quantity Q2And injection pressure pjwf2And (4) trial calculation and search are carried out from small to large until the inflow pressure difference and the outflow pressure difference at the bottom hole node meet the requirement epsilon, and the calculation model is shown as a formula (6).
Figure BDA0003211728030000072
In the formula, QjM is the total dosage3/d；rsf-mThe split coefficient of the injection quantity is distributed for the mth layer, and the dimension is not needed; epsilon is the maximum value of the inflow pressure difference and the outflow pressure difference of the bottom hole node of the first layer, and is MPa. The node analysis model adopts a step-by-step search method in a nonlinear equation set numerical solution method, is simpler, more convenient and faster, and is applied to the technical field of the analysis of the node analysis model>The multilayer dispensing of 2 layers is more advantageous.
(2) Prediction of injection allocation error and injection allocation qualified rate of stratified water injection
Under the condition that reservoir parameters and water injection technological parameters are determined, two-layer injection pressure and actual injection quantity under the working condition can be calculated through a separate injection water injection well node analysis model. And according to the definition of single well injection allocation error, [ design injection amount (last injection amount measured) -actual injection amount (last injection amount measured) ]/design injection amount (last injection amount measured), the injection allocation error can be predicted, and the expression is as follows:
EQ＝[Q(t2)-Q(t1)]/Q(t1) (7)
if only the formation pressure changes at two times, then there are:
[Q，Q1，…，Qm，pjwf1，…，pjwfm](t)＝fw[ (fluid Property: p)w,Bw,μw) (ground line: L)p,εp,Dp) (wellbore 1: L)w1,Hw1,εw,Dw,rw) (wellbore 2: L)w2,Hw2…, (shaft m: L)wm,Hwm(water distribution nozzle 1: 2R)n1,hn1+2Rn1,xn1) (water distribution nozzle 2: 2R)n2,hn2+2Rn2,xn2) …, (water distribution nozzle m: 2R)nm,hnm+2Rnm,xn2) (reservoir 1: h)1,re1,pr1(t),Kw1,s1,pffB (reservoir 2: h)2,re2,pr2(t),Kw2,s2) …, (reservoir m: h)m,rem,prm(t),Kwm,sm) (Water injection Process: p)j,Qmax)]. (8)
The calculation formula of the corresponding injection allocation qualified rate is as follows:
RQ＝1-EQ (9)
(3) prediction of testing and adjusting period of separated layer water injection
According to the descending trend of the formation pressure along with the time, the descending trend is substituted into a separate injection water injection well node analysis model, the change trend of the two-layer injection pressure and the actual injection amount along with the time can be calculated, and the appropriate injection allocation measuring and adjusting period can be predicted by comparing the change trend with the injection allocation requirement. The measured and adjusted cycle is defined as the time interval when the error of two measured and adjusted injections is larger than the requirement, and the expression is as follows:
CYQ＝tn-t1when E isQ＝[Q(tn)-Q(t1)]/Q(t1)＜EQ requirementThen, n is 2,3, 4. (10)
[Q，Q1，…，Qm，pjwf1，…，pjwfm](t)＝fz[ (fluid Property: p)w,Bw,μw) (ground line: L)p,εp,Dp) (wellbore 1: L)w1,Hw1,εw,Dw,rw) (wellbore 2: L)w2,Hw2…, (shaft m: L)wm,Hwm(water distribution nozzle 1: 2R)n1,hn1+2Rn1,xn1) (water distribution nozzle 2: 2R)n2,hn2+2Rn2,xn2) …, (water distribution nozzle m: 2R)nm,hnm+2Rnm,xn2) (reservoir 1: h)1,re1,pr1(t),Kw1,s1,pffB (reservoir 2: h)2,re2,pr2(t),Kw2,s2) …, (reservoir m: h)m,rem,prm(t),Kwm,sm) (Water injection Process: p)j,Qmax)])]. (11)
On the basis of the prediction of the separate injection testing and debugging period, the classification of the testing and debugging wells and the early warning of the testing and debugging can be carried out, and the method comprises the following steps: reservoir parameters of water injection wells of the research block are substituted into a separate injection water injection well node analysis model, injection pressure and injection allocation quantity of each well can be obtained, the injection pressure and the injection allocation quantity are compared with the designed injection allocation quantity of the block, and therefore the wells which do not need to be measured and adjusted can be obtained, and the wells which need to be measured and adjusted can be measured and adjusted at any time, and therefore classification of the injection wells can be achieved, and measurement and early warning can be carried out.
Example 1 prediction of injection allocation error and injection allocation qualification rate of stratified injection
Example calculation is carried out, and the input known parameters are taken from data of L42-20 wells in G83 area of Changqing oil field, including L42-20 well pressure test result report, L42-20 well separate injection allocation test result report and G83 area length 4+5 length 6 oil deposit basic data, as shown in Table 1, wherein the opening degrees of water nozzles at two layers are all set to be 1.0, and the formation pressure of the water injection well can be increased along with time.
Table 1 known parameters
Figure BDA0003211728030000091
Figure BDA0003211728030000101
The results of the calculation of dispensing and injection allocation errors are shown in table 2:
TABLE 2 calculation of dispensing and filling errors
Figure BDA0003211728030000102
Example 2 prediction of stratified water injection trim cycles
Performing example calculation, wherein the input known parameters are shown in table 3, the opening degrees of the two-layer water nozzles are all set to be 1.0, and the fitting relation of the formation pressure and the time is assumed to be pr＝pr0+0.01t，EQ requirement＝50％。
Table 3 known parameters
Figure BDA0003211728030000103
Figure BDA0003211728030000111
The results of the dispensing cycle calculation are shown in table 4 and fig. 2:
TABLE 4 calculation results of dispensing cycle
Figure BDA0003211728030000112
Therefore, the measured and adjusted period of the well at the moment is calculated to be 40-50 days.

Claims (8)

1. A method for determining a zonal water injection testing and regulating period of a tight oil reservoir is characterized by comprising the following steps:
establishing a layered water injection multi-layer node analysis model on the basis of the single-layer general water injection node model;
solving the layered water injection multi-layer node analysis model until the inflow and outflow pressure difference at the bottom hole node meets the maximum value required by the inflow and outflow pressure difference of the first layer bottom hole node;
obtaining two-layer injection pressure and actual injection quantity under the working condition through a layered water injection multi-layer node analysis model, designing injection quantity-actual injection quantity/designed injection quantity according to the definition of single well injection distribution error, and predicting the injection distribution error;
and substituting the ground pressure into a layered water injection multilayer node analysis model according to the descending trend of the ground pressure along with time to obtain the change trend of the two-layer injection pressure and the actual injection amount along with time, comparing the change trend with the injection allocation requirement, and predicting the injection allocation measuring and adjusting period.
2. The method for determining the interval water injection testing and adjusting period of the tight oil reservoir according to claim 1, wherein in the single-layer cage system water injection well node analysis, the division of the pressure drop system comprises the following steps: pressure drop Deltap of ground horizontal pipe1Pressure drop Δ p of underground vertical pipe2Pressure drop Δ p of the mouth flow3And the pressure drop Δ p of the injection water in the ground4Four parts; the pipe flow pressure drop is calculated by a Darcy formula, the nozzle flow pressure drop is calculated by a nozzle flow pressure drop model, and the seepage flow pressure drop of the injected water in the ground is calculated by a plane radial flow pressure drop model; the pressure drop system division of the layered water injection well node model is characterized in that the flow pressure drop of a shaft pipe, the flow pressure drop of a nozzle and the seepage pressure drop are divided into a plurality of parts according to a plurality of layers, wherein the parts are respectively delta p2-1、…、△p2-m，△p3-1、…、△p3-m，△p4-1、△p4-mAnd m is the number of layers of the stratified water injection.
3. The method for determining the interval water injection testing and adjusting period of the tight oil reservoir according to claim 2, wherein the specific formula of the pressure drop of each part is as follows:
Figure FDA0003211728020000011
wherein Q is the amount of injected water, m3/d；LpIs the ground pipeline length, m; dpIs the ground pipeline inner diameter, m; a. thepIs the internal cross-sectional area of the ground pipeline, m2；
Figure FDA0003211728020000012
In the formula, Lw、HwWell depth and vertical depth, m, respectively; dwIs the inner diameter of the oil pipe, m; a. thewIs the internal cross-sectional area of the oil pipe, m2；λp、λwThe coefficients of flow friction resistance in the ground pipeline and the oil pipe are respectively, and the method is dimensionless; subscripts 1, m refer to the first and mth layers, respectively, m ═ 1, 2, …, mmax；mmaxThe maximum number of layers is injected by layers without dimension;
Figure FDA0003211728020000021
in the formula DnThe inner diameter of the water distribution nozzle is m; a. thenFor the overflow area of the water distribution nozzle, the overflow area m of a water nozzle with adjustable flavor, such as a U-shaped throttle orifice2；CdFor adjusting the flow coefficient of the tap, Cd(x)＝-3.1004x4+8.7432x3-8.8037x2+3.64x +0.2635, dimensionless; x is the opening degree of the water nozzle, 0-1.0 and is dimensionless;
Figure FDA0003211728020000022
in the formula, h is a reservoir layerEffective thickness, m; kwIs water phase permeability, μm2；rwIs the wellbore radius, m; r iseThe water injection wave radius is m; s is epidermal factor, and is dimensionless; rhowAs density of the aqueous phase, kg/m 3; mu.swIs the aqueous phase viscosity, mPa.s; b iswIs the volume coefficient of the water phase and is dimensionless;
establishing a layered water injection node analysis model, taking the bottom hole flow pressure of the 1 st layer as a solution point, and using an inflow dynamic equation as shown in the formula, a layer 1 outflow dynamic equation and the 2 nd to m th layersmaxThe layer outflow dynamic equation and the relation among the injection quantities of the multiple layers form a node analysis model of the multiple-layer injection water injection well, and the node analysis model is shown as a formula (5);
Figure FDA0003211728020000023
in the formula, pjwf-inIs the bottom hole pressure of the inflow node, Pa; p is a radical ofjwf-outIs the bottom hole pressure of the outflow node, Pa; p is a radical ofrIs the formation pressure, MPa.
4. The tight oil reservoir zonal injection testing and adjusting period determination method as claimed in claim 1, wherein a stepwise search method in a nonlinear equation set numerical solution method is adopted for solving, a split coefficient of injection allocation is assumed first, and a ratio r of upper injection flow and total injection flow is assumed firstsfjAnd the total injection quantity Q is the value rsfj epsilon (0, 1), and Q epsilon [0,1600]Then substituting into the upper layer outflow dynamic equation to calculate to obtain the total injection quantity and Q, and the upper layer injection quantity Q1And injection pressure pjwf1Then substituting the lower layer outflow dynamic equation to obtain the lower layer injection quantity Q2And injection pressure pjwf2Searching and calculating one by one from small to large until the inflow pressure difference and the outflow pressure difference at the bottom hole node meet the requirement epsilon, wherein the calculation model is shown as a formula (6);
Figure FDA0003211728020000031
in the formula, QjM is the total dosage3/d；rsf-mThe split coefficient of the injection quantity is distributed for the mth layer, and the dimension is not needed; epsilon is the maximum value of the inflow pressure difference and the outflow pressure difference of the bottom hole node of the first layer, and is MPa.
5. The method for determining the interval water injection testing and adjusting period of the tight oil reservoir according to claim 1, wherein the injection allocation error is expressed as follows:
EQ＝[Q(t2)-Q(t1)]/Q(t1) (7)
if only the formation pressure changes at two times, then there are:
[Q，Q1，…，Qm，pjwf1，…，pjwfm](t)＝fw[ (fluid Property: p)w,Bw,μw) (ground line: L)p,εp,Dp) (wellbore 1: L)w1,Hw1,εw,Dw,rw) (wellbore 2: L)w2,Hw2…, (shaft m: L)wm,Hwm(water distribution nozzle 1: 2R)n1,hn1+2Rn1,xn1) (water distribution nozzle 2: 2R)n2,hn2+2Rn2,xn2) …, (water distribution nozzle m: 2R)nm,hnm+2Rnm,xn2) (reservoir 1: h)1,re1,pr1(t),Kw1,s1,pffB (reservoir 2: h)2,re2,pr2(t),Kw2,s2) …, (reservoir m: h)m,rem,prm(t),Kwm,sm) (Water injection Process: p)j,Qmax)]；(8)
The calculation formula of the corresponding injection allocation qualified rate is as follows:
RQ＝1-EQ (9)。
6. the method for determining the interval period of the zonal injection testing and the debugging of the tight oil reservoir according to claim 1, wherein the interval period of the testing and the debugging is defined as the interval period when the error of the two times of testing, debugging and injection allocation is greater than the requirement, and the expression is as follows:
CYQ＝tn-t1when E isQ＝[Q(tn)-Q(t1)]/Q(t1)＜EQ requirementThen, n is 2,3, 4. (10)
[Q，Q1，…，Qm，pjwf1，…，pjwfm](t)＝fz[ (fluid Property: p)w,Bw,μw) (ground line: L)p,εp,Dp) (wellbore 1: L)w1,Hw1,εw,Dw,rw) (wellbore 2: L)w2,Hw2…, (shaft m: L)wm,Hwm(water distribution nozzle 1: 2R)n1,hn1+2Rn1,xn1) (water distribution nozzle 2: 2R)n2,hn2+2Rn2,xn2) …, (water distribution nozzle m: 2R)nm,hnm+2Rnm,xn2) (reservoir 1: h)1,re1,pr1(t),Kw1,s1,pffB (reservoir 2: h)2,re2,pr2(t),Kw2,s2) …, (reservoir m: h)m,rem,prm(t),Kwm,sm) (Water injection Process: p)j,Qmax)])]；(11)。
7. The method for determining the zonal water injection testing and dispatching cycle of the tight oil reservoir according to claim 1, wherein the design injection allocation is the previous testing and dispatching injection allocation; the actual dispensing amount is the dispensing amount measured at the next time.
8. A tight oil reservoir zonal water injection testing and adjusting period determination system is characterized in that the tight oil reservoir zonal water injection testing and adjusting period determination method based on any one of claims 1 to 7 comprises the following steps:
the model establishing module is used for establishing a layered water injection multi-layer node analysis model on the basis of the single-layer general water injection node model;
the solving module is used for solving the layered water injection multi-layer node analysis model until the inflow and outflow pressure difference at the bottom hole node meets the maximum value required by the inflow and outflow pressure difference at the bottom hole node of the first layer;
the injection allocation error prediction module is used for obtaining two-layer injection pressure and actual injection amount under the working condition through a layered water injection multi-layer node analysis model, designing injection allocation amount-actual injection allocation amount/designed injection allocation amount according to the definition of single well injection allocation error, and predicting the injection allocation error;
and the injection allocation measuring and adjusting period prediction module is used for substituting the layered water injection multi-layer node analysis model according to the descending trend of the formation pressure along with the time to obtain the change trend of the two-layer injection pressure and the actual injection amount along with the time, comparing the change trend with the injection allocation requirement and predicting the injection allocation measuring and adjusting period.
CN202110932795.XA 2021-08-13 2021-08-13 Method and system for determining zonal water injection testing and regulating period of tight oil reservoir Pending CN113445972A (en)

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